Product information: ZM-DS4F Dual Stereo Headphones - Black

Unlike regular stereo headphones, the Dual Stereo Headphones are equipped with two diaphragms per channel. The smaller diaphragm funtions as the tweeter, while the larger diaphragm, that is positioned behind the smaller diaphragm, funtions as a woofer, similar to a 2-Way speaker. The 2-Way design not only broadens the headphones' frequency response range for deep bass & clear highs, but also produces a well balanced response throughout its responsive range. They are optimized for MP3 Players, PMP, Mobile CD/MD Players and when using the ZM-DS4F with a mobile device, they will provide a strengthened mid and low sound.